German Nuclear “Wunderwaffen” in 1945?

Since World War II the history of the Third Reich has been written – for the most part – in English by the victors. Understandably, the picture so painted of German life and of the accomplishments of the people under National Socialism has not been flattering, with the exception perhaps of German scientific and technological achievements, the value of which few would deny. As testimony to this appreciation, at the end of the war, with Germany in total ruins, the British, Americans, French, and Russians all competed in a frenzied race to recruit, bribe, or kidnap leading German scientists, to loot German industrial secrets, confiscate patents, and take whatever else their own societies could not provide. Because Germany did not build nuclear bombs during the war, Western analysts believed that German scientists were incapable of doing so. Today, however, books are being written in both Russia and Germany that considerably alter the previous prejudiced views of German nuclear competence entertained by the victors. Two such books, The Atomic Bomb and the Third Reich[1] and Hitler’s Bomb,[2] written by young German historians, now report advances made in nuclear physics by German scientists late in the war and in the immediate postwar period and later in the employ of their Soviet kidnappers and their American employers that had not been noted earlier.

The arguments concerning the seeming failure of the Germans to build a bomb ranged from the prejudiced contention that the nuclear physicists under the National Socialist government were simply incompetent and incapable of building such a complex bomb to the more kindly argument that leading German physicists out of the noblest of motives had deliberately undermined and discouraged the Nazis’ attempt to build the bomb. Although now somewhat dated, David Irving’s The Virus House (Simon & Schuster, New York, 1967) remains the earliest and most objective study of German efforts during the war.[3] Evidence now available from German and Russian sources (the Soviets had confiscated the scientific papers of the Kaiser Wilhelm Institute of Physics in Berlin) now suggest that the Germans had quite possibly conducted several field tests of a nuclear device in the spring of 1945, thereby demolishing both arguments. Some German scientists were indeed working on the development of a nuclear weapon; others preferred to work on non-military applications of nuclear power.

While Heisenberg, von Weizäcker, and Albert Speer, the economic tsar, and others very likely did try for various reasons to dissuade their government from building the bomb, lesser-known German physicists of the time allegedly attempted to develop a nuclear weapon, albeit a much smaller device than those used on Hiroshima and Nagasaki.

Among the better known German physicists who were interred and interrogated by the Western Allies at Farm Hill, England, after the war were: Werner Heisenberg, Carl Friedrich von Weizsäcker, Otto Hahn, Max van Laune, Erich Bagger, Kurt Diebner, Walther Gerlach, Paul Harteck, Horst Korsching, and Karl Wirtz. Another group of equally competent physicists, including Manfred von Ardenne, Gernot Zippe, Peter Thiessen, Max Steenbeck, and Gustav Hertz (Hertz, being half-Jewish, went willingly) were simply kidnapped to the Soviet Union and ordered to reproduce their work in Sukhumi, a Georgian city on the Black Sea. The Soviets promised to release them after they had completed their assignments, a promise they eventually kept.

As early as 1940, all German nuclear physicists and a considerable segment of the military were aware of the potential of developing weapons of great destructive power based on the release of energy from nuclear fission/fusion. Although von Weizsäcker and Heisenberg later distanced themselves from the development of nuclear weapons (uranium and plutonium) for wartime use, the former by accepting a professorship in Strasbourg and the later by concentrating on reactor development, both knew exactly the destructive potential the bomb would have.

For example, in 1941 Weizsäcker submitted a patent application (cited by Karlsch) that read:[4]

“The production of element 94 (plutonium) in practically useful amounts is best done with the ‘uranium machine’ [nuclear reactor]. It is especially advantageous – and this is the main benefit of the invention – that the element 94 thereby produced can easily be separated from uranium chemically. With regard to energy per unit weight this explosive would be around ten million times greater than any other existing explosive and comparable only to pure uranium 235. [Further, he describes a] process for the production of explosive energy from the fission of element 94, whereby element 94 is brought together in such amounts in one place, e.g., a bomb, so that the overwhelming majority of neutrons produced by fission excite new fissions and do not leave the substance.”

In February 1942 Heisenberg, while still the most prominent figure in the German Uranium Project (Uranverein), gave a public lecture on the possibilities of developing nuclear weapons, in which he concluded that energy generation from uranium fission was undoubtedly possible, providing the enrichment of isotope U-235 is successful. Isolating U-235, he contended, would lead to an explosive of unimaginable power. In another lecture in the summer of 1942 Heisenberg spoke of America’s exceptionally great interest in nuclear weaponry and predicted that, if the war lasted long enough, the technical realization of atomic nuclear energies could play a decisive role in the war.

Because of his notoriety and brilliance (he had earlier won a Noble Prize) Werner Heisenberg and his associates became the main focus of Allied concern, even to the point where the Allies planned to assassinate him at a conference in Switzerland before he could develop a German bomb.[5] Then, as now, American intelligence tended to concentrate on celebrity figures, often disregarding lesser-known but extremely competent individuals. Actually, Heisenberg was competing with a lesser-known German team in a race to get an atomic pile critical. According to Mayer, Mehner, and Karlsch, the authors of the books under review, it was precisely this other group of lesser-known German physicists, working directly for the German Armed Forces and under SS protection, that actually developed an atomic pile that went critical. This team, according to Karlsch, also experimented with a nuclear device in the last months of the war in a desperate attempt to stop the Russian juggernaut.

With the tide of war turning, Army officials, now convinced that pure U-235 could become an explosive a million times more powerful than conventional explosives, intensified their interest in possible military applications of the Uranium Project. The Reich Research Council and the German Army took charge of the program. Heinrich Himmler was appointed head of the German Army Weapons program in the summer of 1944. Party member Kurt Diebner, always closest to the Army Weapons Center operations, assumed responsibility for nuclear weapons development. With the exception of Kurt Diebner, who was a member of the National Socialist Party, the other German physicists (like most scientists everywhere) were for the most part apolitical

According to the authors, the main effort of the Germans to develop a nuclear weapon took place in the Arnstadt-Wechmar-Ohrdruf (AWO) triangle in Thuringia.

Kurt Diebner and Walther Gerlach, the scientific leaders of the research team attempting desperately to develop a nuclear weapon in the last days of the war, were housed in the basement of the high school near Arnstadt in the Jonastal valley.[6] SS General Hans Kammler, himself a doctor of engineering, headed the protective forces surrounding the experimental area.

Extensive underground galleries to house various facilities were excavated in Jonastal; the army training grounds in Ohrdruf was used as the bomb test range; and a reactor, better designed than Heisenberg’s in Haigerloch, was situated in the town of Gottow. Also involved in this project, according to the authors, was the research office of the Reichspost under Wilhelm Ohnesorge as well as offices of the Skoda Works in Prague. The Siemens electrical enterprises were involved in critical stages of the project. Laborers were drawn from various concentration camps in the area. Also, German naval authorities, including Admirals Karl Witzell and Wilhelm Rhein as well as physicists Otto Haxel, Fritz Houtermans, and Pascual Jordan, took an active part in researching the potential of nuclear power. The Navy’s main interest was of course in the development of the “uranium machine” as the basis for propulsion systems for surface ships and submarines.[7]

It is the contention of the authors of both books that the Germans actually succeeded in developing and testing the prototypes of a small nuclear device (a subcritical 100-g A-weapon) as well as a delivery system, the long-range A9/A10 missile whose characteristics and capabilities were comparable to the later U.S. Titan II. The project was code-named S-III (S = Sondervorhaben, Special Project). The code name “Olga” referred to the so-called “America Rocket.” Mayer and Mehner provide U.S. aerial photographs taken by the 7^th US Photo Group of the launch pad of the prototype rocket, which the authors believe was successfully tested on 16 March 1945.

Moreover, as Karlsch makes clear, the Soviet government was also informed about the German nuclear experiments. A Soviet intelligence report Karlsch introduces, submitted to Stalin on March 23, 1945 by Kurchatov, the head of the Soviet Nuclear Bomb Program, on the initiative of the head of military intelligence (GRU) in Germany, Lieutenant General Il’ichëv,[8] reads:[9]

“Just recently, the Germans detonated two massive explosions in a wooded area of Thuringia under the greatest secrecy. Trees at a distance of 500 to 600 meters were knocked down. Prisoners used in the experiment were killed, often no remains were found. Others suffered facial and body burns. A strong shock wave and high temperatures accompanied the bomb detonations. The bombs were spherical in shape and had a diameter of 130 cm.”

Karlsch maintains that the Gattow reactor, combined with the output of centrifuges, and electromagnetic mass separators – all of which were available – could have produced the several hundred grams of enriched uranium required by the device. Mayer and Mehner believe that a French-designed betatron and Norwegian-built heavy water facilities were also at the Germans disposal. Based on Schumann’s hollow charge principle for focusing the energy to a single spot in the shell, the device so developed and tested, according to Karlsch, created a shock wave, a heat wave, and released considerable radioactivity. In all, three tests were conducted. The earliest occurred in October 1944 on Rügen Island. It was witnessed by Italian war correspondent Luigi Romersa who informed Mussolini of the event.[10] The final test, and the one about which the most information is available, took place on 4 March 1945 in Ohrdruf.

In a whole series of sensationalistic books, Thomas Mehner has written about secret Third Reich Weapon research, here with the title “Nuclear Target New York” on long-range missles and space vehicles to attack major U.S. cities.

Karlsch concludes that the Ohrdruf device was more of a small, tactical-type device, much less powerful than the U.S. bombs being developed at the time, the critical mass of which was about 50 kilograms of U-235. The destructive range of the German device was about 500 meters in diameter. Its importance today is that it was what is now referred to as a kind of “dirty” bomb. Regrettably, in the German experiment several hundred people (mostly souls from a nearby concentration camp), who were used as support personnel, are reported to have been killed by the experiment.

The authors of the books under review surmise that it is precisely because several hundred innocent individuals died in the German experiment that Diebner, Gerlach, and others involved in these tests have never spoken openly about their work during the last months of the war. Fear of being accused as war criminals is believed to have kept all involved mute.

Karlsch provides both eyewitness accounts of the test as well as forensic (crater photo, ground sampling for radioactive isotopes, etc.) on-site evidence to support his literature and document studies. Ground-sampling tests first done on Rügen Island yielded disappointing results, which Karlsch attributed to soil erosion over the years. Similar tests conducted in the Ohrdruf test range showed a significant increase in cesium values the closer one approached to the center of the explosion; cobalt 60, an artificial element that occurs when fast neutrons strike iron or nickel, was also detected. Gerald Kirchner of the German Federal Office for Radiation Protection maintains that so far there is no evidence of a nuclear bomb burst. However, Uwe Keyser of the German Federal Technical Physics Office in Braunschweig insists that the measured values of radioactive substances at the site have been so significant that the explosion of a simple nuclear device cannot be excluded.[11]

Eyewitness accounts of the event include statements by a worker who helped cremate those who perished on improvised pyres right on the test site, comments made by Werner Grothmann, Himmler’s adjutant (the tests were run under the supervision of the SS), as well as the following graphic statement by Cläre Werner, who witnessed the test from the heights of the Wachsenburg:[12]

“I can still remember the day very well. It was March 4, 1945. We had scheduled a birthday party for that evening, but it was cancelled. In the afternoon the BDM [Federation of German Girls] of Gotha was on the mountain. Hans was also there to help out and told us that world history would be written today in this area. It would be something the world had never seen before. We were to go on the mountain that evening and look off in the direction of Lake Röhren. He didn’t know himself what the new thing would look like. So we were on the site at 8 PM. At half past 9 PM the area behind Lake Röhren lit up like as though a hundred lightning bolts had struck. It was red inside and yellow on the outside. You could read the newspaper by the light. It all happened very quickly and we couldn’t see anything except what sounded like a squall, after which everything was quiet. I, like many inhabitants from Lake Röhren, Holzhausen, Mühlberg, Wechmar and Bittstädt had nose bleeds, headaches, and felt pressure on the ear, the next day. At about 2 PM there were about 100-150 SS-men on the mountain. They asked where the bodies were, where they were taken, and who was there. We didn’t know anything and they asked us if they were here in the ‘Burg Object.’ I told them they were on the Veste Wachsenburg, which the people always call the Burg (mountain). A motorcyclist reported that the Burg could be reached via Ringhofen. Then the cars drove from the Burg to Mühlberg. I saw that from there they drove to the test area.”

Karlsch also cites an exuberant exclamation made by SS Reichsführer Heinrich Himmler in March 1945:[13]

“We have not yet deployed our last miracle weapon. To be sure, the V1s and V2 are effective weapons, but our decisive miracle weapon will demonstrate such results that no one can even imagine. One or two strikes and cities like New York or London will disappear from the face of the earth.”

Elements of Patton’s 3^rd Army occupied the AWO area on 12 April 1945 and immediately reported their findings to higher headquarters. American forces quickly began to dismantle some of the facilities together with copious documents for shipment back to the United States. Soviet forces relieved the Americans in July 1945 and continued investigating the area. A Major Robert Allen of Patton’s forces wrote about what he encountered, as did a Soviet defector, Gregory Klimov, formerly associated with the Soviet Military Administration in Germany, about the Red Army’s finds.[14]

As later evidence of Diebner’s advanced work late in the war, Karlsch notes that as soon as German physicists were permitted by the Allies to resume their work in the postwar period (1955), Diebner submitted several noteworthy patents not just on reactors but also on the construction of a hydrogen bomb. Diebner also wrote about the potential use of nuclear energy in controlled underground explosions, in port construction, the shipbuilding industry, and for ship propulsion, including submarines. Indeed, Germany commissioned the world’s second (the US SAVANNAH was first) nuclear-powered merchant-research ship, OTTO HAHN, in 1968. The 15,000-t ship sailed 650,000 nautical miles in 10 years without suffering any technical problems. Nor did the eventual mating of nuclear propulsion with submarines escape the wartime German researchers.

Also, with respect to methods of building a hydrogen bomb, Karlsch reviewed the papers of physicist Erich Schumann, director of the research center of the German Army Weapons-Research Office. Schumann claims that as early as 1944 he had found a way through the use of conventional explosives to generate sufficiently high temperatures of several million degrees Celsius and extreme pressures to produce nuclear fusion. According to Schumann, two hollow charges, directed against each other under special conditions, releases enough energy to create nuclear fusion. Schumann believes that the Diebner team actually tested this procedure at the Ohrdruf test range in Thuringia.

In mid-April 1945 the German transport and minelayer submarine U-234,[15] also referred to as an undersea aircraft carrier, was deployed by the German High Command to Japan carrying examples of the latest high-tech German developments in armaments (radar, jet engines, Henschel HS-293 glider bombs, Me-262 jet fighters, a V2 rocket, etc.) for use by its Japanese ally. Most importantly, U-234, after it surrendered to the United States Navy when the war ended, was found to carry some 560 kilograms of uranium oxide in its cargo.[16] Western analysts have speculated as to its intended use in Japan. Some think it was to support Japan’s own nuclear program, others speculate that it was for the production of synthetic methanol used in aviation fuel, but others have suggested that perhaps it was intended for the production of “dirty” bombs (atomic material combined with conventional explosives) by the Japanese to be dropped over the U. S Pacific coast.

Although the U-234 also carried German civilian engineers and scientists, none are said to have been specialists in nuclear matters. The contents of the documents seized on the U-234 have not been made public.

With regard to the development of so-called “dirty” bombs, mention must be made of the group of German scientists forced to work in the Soviet Union. The head of the group, Manfred von Ardenne, was ordered by his captors to build the bomb. Von Ardenne explained to the Russians that it was first essential to perfect an efficient method of enriching uranium to fuel, as it were, the bomb. Upon receiving the permission of the Soviets to make the enrichment of uranium first priority, von Ardenne appointed Max Steenbeck and Gernot Zippe responsible, the former being the theoretician and the latter the experimentalist. Within five years Zippe had built a highly cost- and task-efficient centrifuge model, which, by 1953, the Russians had adopted and were already building full-scale plants to accommodate and implement them. The Soviet authorities then agreed to permit the Germans to return to their shattered fatherland, but only after a “cooling-off” period of several years. Zippe utilized these years as he endured them by learning English.

He returned home in July 1957 and was soon commissioned by the U.S. Atomic Energy Commission to build such a centrifuge system for the United States. Since the Russians did not permit Zippe to take any notes, papers, or drawings of his work in the Soviet Union, Zippe reproduced his centrifuge entirely from memory. The centrifuge, which used only about 10% as much electricity as the established gaseous diffusion process, was much in advance of existing designs in the West and was therefore quickly accepted here and in the Urenco consortium in Europe. The United States, until Zippe’s major centrifuge contribution, had been using energy-guzzling electromagnetic calutrons for isotope separation.

In effect, Zippe not only revolutionized the centrifuge method throughout the world but, by doing so, also dangerously lowered the nuclear threshold, making the development of nuclear weapons accessible to many poorer nations.

For example, by chance Abdul Q. Khan, now known as the “Father of the Pakistani Bomb” and the “Father of Nuclear Proliferation,” also worked at Urenco and soon became thoroughly familiar with the principles of Zippe’s centrifuges. Shortly after leaving Urenco Khan undertook to instruct colleagues in Iraq, South Africa, Pakistan, and Brazil in its development.

Under the terms of the cease-fire in the first Gulf War, the International Atomic Energy Commission’s inspection team confirmed that Iraq was indeed trying, but as yet not succeeding, in realizing the benefits of the centrifuge system. Another German centrifuge expert, Bruno Stemmler, who was also familiar with the work done in Urenco, had earlier (1988-89) assisted the Iraqis in adopting the centrifuge system, but subsequently was ordered by Germany to sever his collaboration.[17] There is little doubt that the Iraqis were attempting to develop nuclear weaponry utilizing Zippe’s method before they were dissuaded forcibly after the first Gulf War.

Since 1990 the professional literature on Zippe’s centrifuges has become so voluminous that almost any country with the requisite resources and professionals can attempt to duplicate Zippe’s original work.[18]

Reviewer’s Comments

Both books herein reviewed, Die Atombombe und das Dritte Reich and Hitler’s Bombe, especially the former, are highly speculative and inconclusive. The use of the term “atomic bomb” in the titles of these books is entirely misleading – an example of advertising hype by German publishing houses. The nuclear device, about which the German authors speak, was probably even less powerful than the smallest known nuclear tactical weapon in the Western arsenal, the XW-54 Davy Crocket. Without the bombs and the bombast, these books still tell the fascinating story of the desperate, heroic efforts of German engineers and scientists, in the face of imminent defeat, to turn the tide of battle.

The Mayer-Mehner book relies heavily on hearsay and the informative letters of the mysterious Hans Michael Ritterman, alias Hans David Hoffmann, who, we are told, occupied a high position as a construction engineer in the AWO triangle from 1938 to 1945. Upon the arrival of the American forces he became a collaborator with the occupying forces and was awarded Jewish identification papers and the privilege of living in Israel as a reward. As the ultimate insider, his information provides the backbone of the Mayer-Mehner book. Conveniently for the authors, but inconvenient for anyone wishing to vet him, he is said to have died in 2001. Unfortunately, other important key figures in the story about the AWO triangle, as for example SS General Hans Kammler, were also officially declared unaccounted for after the war and assumed dead, although they may have been held incommunicado for interrogation by either U.S. or USSR authorities after the war and given new identities for their cooperation. The death of SS boss Heinrich Himmler after the war, now believed by some to have been at British hands,[19] was particularly unfortunate in that he would have known most about the experiments.

The genre of the Mayer-Mehner book is very much similar to the many speculative books and articles written, for example, about Germany’s Neu-Schwabenland expedition to Antarctica in 1938-1939. For years it was rumored that the Germans had used the area to build submarine pens and to launch flying saucers, while in fact it was nothing more than a scientific expedition, possibly to lay the groundwork for an official claim to the area. As for the Ritterman letters, one recalls the several volumes of journals, ostensibly written by the former head of the Gestapo (German secret police) Heinrich Müller. A good writer with a fertile imagination can invent all manner of things to dress up a bare topic. He can even resurrect ghosts from the past to lend verisimilitude to his story.

The more recent Karlsch book Hitler’s Bombe, however, is much better researched and documented, and far more convincing. It cannot, and indeed has not, been dismissed out of hand. To begin with, Karlsch makes no reference whatsoever to a mysterious Hans Ritterman. Quite the contrary, Karlsch has consulted with and sought the advice of contemporary scientists whose opinions he cites. Among the original documents he includes in his work are:

1. The von Weizäcker patent applications;
2. Diebner’s 1942 report of the Army Weapons Center in which in states that – theoretically – an atomic bomb can be built;
3. formulas for the fusion of light elements and the critical mass for a plutonium bomb, written by Friedrich Berkei, Diebner’s deputy. (Incidentally, Berkei died in 1966 at age 55 of radiation sickness.);[20]
4. a letter written by Diebner in late 1944 to Heisenberg reporting on reactor problems;
5. Gerlach’s 1944 notes, sketches, and formulas for thermo-nuclear reactions;
6. a Schumann letter to Ernst Telschow concerning tests on the fusion of light elements;
7. the Kurchatov report on German atomic bomb work.

Even the publication of a drawing of the German atomic bomb in reference,[4] made after the war had ended, is not conclusive in any way. A drawing of the bomb is far removed from actually building it.

Although the title of his book, Hitler’s Bomb, suggests more than the author could actually deliver, Karlsch defines the main thesis of his book much more soberly. He states very clearly that German scientists did not develop a nuclear device at all comparable to the American or Soviet hydrogen bombs of the 1950s. However, they knew in general terms how they functioned and were in a position to excite an initial nuclear reaction by means of their perfected hollow-charge technology. Only further research will determine whether their experiment represented fusion or fission reactions, or both.

Without access to the dismantled equipment and documents confiscated by the occupying forces, hard physical evidence proving that a nuclear device was indeed detonated in the Ohrdruf test grounds is almost impossible to find. Consequently the authors have had to rely on detective work and the accumulation of circumstantial evidence, which still remains inadequate. Uwe Keyser, a nuclear physicist from the German Federal Institute of Physics and Technology, currently testing soil samples at the site, has found that traces of radioactive substances are sufficiently abnormal as to warrant further investigations.

Whatever the final verdict is on the 1945 nuclear tests, the achievements of the German wartime physicists in the face of limited resources, the exigencies of war, the pressure of time, their isolation from the rest of the world, and the lack of essential materials were unquestionably remarkable. With but a handful of scientists, wartime German science, especially nuclear physics and rocketry, maintained and in many cases even surpassed world standards.

Notes